Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
  • H04L25/03828—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties
  • H04L25/03834—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties using pulse shaping
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/69—Spread spectrum techniques
  • H04B1/7163—Spread spectrum techniques using impulse radio
  • H04B1/717—Pulse-related aspects
  • H04B1/7174—Pulse generation

Definitions

• This invention addresses the need to transport high bit-rate data over wired or wireless means using specially modulated radio frequency carrier waves.
• a technique is described in this disclosure that uses SAW filters as a modulator in addition to their conventional use as filters. This technique exploits the impulse response of the SAW filter by exciting the filter with a narrow pulse train producing a carrier-less impulse radio system with limited bandwidth, low average power, but high peak power.
• Modulation is the fundamental process in any communication system. It is a process to impress a message (voice, image, data, etc.) on to a carrier wave for transmission.
• a band-limited range of frequencies that comprise the message (baseband) is translated to a higher range of frequencies.
• the band-limited message is preserved, i.e., every frequency in that message is scaled by a constant value.
• the three key parameters of a carrier wave are its amplitude, its phase and its frequency, all of which can be modified in accordance with an information signal to obtain the modulated signal.
• modulators There are various shapes and forms of modulators.
• conventional Amplitude Modulation uses a number of different techniques for modulating the amplitude of the carrier in accordance with the information signal. These techniques have been described in detail in "Modern Analog and Digital Communication Systems" by B.P. Lathi.
• conventional Frequency / Phase Modulation uses a number of different methods described in a number of textbooks. In all these techniques, carrier (which is a high frequency sinusoidal signal) characteristics (either amplitude, frequency, phase, or combination of these) are changed in accordance with the data (or information signal).
• carrier which is a high frequency sinusoidal signal
• characteristics either amplitude, frequency, phase, or combination of these
• modulator is described in this document that does not use a carrier for modulation. Modulation is accomplished by exploiting the impulse response of Band Pass Filters.
• band pass filters are used to band limit the bandwidth of the signal. For example, they are used in transmitters to allow necessary signal to pass to the next stage and in receivers they are used to block any unwanted signal. They are integral part of any communication system and have numerous advantages.
• Band Pass filters come in many shapes and forms. Most of the communication systems these days use SAW (Surface Acoustic Wave) filters. Saw filters are band pass filters. They use a piezoelectric crystal substrate with deposited gold electrodes. SAW filters are capable of replacing discrete LC band pass filters in certain wideband applications between 20MHz and IGHz. Their filter skirts, or shape factor are the sharpest of all the filter structures.
• SAW filters Since they are etched on a printed circuit board, they save a lot of circuit board real estate and are thus easier to implement
• the primary use of SAW filters is to filter unnecessary signals such as band limiting a transmitter output.
• a technique for using SAW filters as modulators has been described by the inventor in another patent titled "Carrier-less Modulator using SAW filters", U.S. Application No. 60/781,718, however, the current modulation technique is significantly different than the one described in the earlier patent application.
• a series of narrow pulses (representing one modulation event) is applied to the input of the SAW filter.
• the SAW filter being a resonant device, rings at the fundamental frequency thus modulating the incoming pulse train without using a carrier for modulation.
• any interfering signal in that spectrum must be tolerated and mitigated within the receiver.
• Many schemes exist to mitigate the interference Some of these include selective blocking of certain sections of spectrum so as not to hear the interferer, OFDM schemes that send redundant copies of the information in the hope that at least one copy will get through interference, and other more exotic schemes that require sophisticated DSP algorithms to perform advanced filtering.
• UWB systems have somewhat of a "bad reputation" because they at least have the potential to cause interference. A heated discourse has gone on for years over the potential that UWB systems can cause interference to legacy spectrum users.
• Tri-State Integer Cycle Modulation (TICM) and other Integer Cycle Modulation techniques were designed by Joe Bobier and the inventor of this application to help alleviate this massive and growing problem which has now become known by its commercial designation, xG Flash Signaling. Its signal characteristics are such that absolute minimal sideband energy is generated during modulation but that power spectrum density is quite wide relative to the information rate applied. Also, a narrower section of the power spectrum output can be used to represent the same information.
• the technique of modulation disclosed herein is primarily applicable to these types of single cycle systems.
• SAW filters Like any other band pass filters, SAW filters also have an impulse response.
• the impulse response depends on the bandwidth of the filter.
• a technique is described in this disclosure that uses the impulse response of the filter to modulate the incoming data signal without using a carrier for modulation by exciting the filter with a narrow pulse train producing an impulse radio system with limited bandwidth, low average power, but high peak power.
• TCM Tri-State Integer Cycle Modulation
• band pass filters are used to band limit the bandwidth of the signal. For example, they are used in transmitters to allow necessary signals to pass to the next stage and in receivers they are used to block any unwanted signals. They are integral part of any communication system and have numerous advantages. Band Pass filters come in many shapes and forms. Most of the communication systems these days use SAW (Surface Acoustic Wave) filters. SAW filters are band pass filters.
• SAW filters Their filter skirts, or shape factor are the sharpest of all the filter structures.
• the primary use of SAW filters is to filter unnecessary signals and are commonly used for band limiting a transmitter output.
• a technique is described in this document that uses SAW filters as a modulator in addition to their conventional use as filters. This technique exploits the impulse response of the SAW filter by exciting the filter with a harrow pulse train producing a carrierrless impulse radio system with limited bandwidth, low average power, but high peak power.
• FIGURE 1 is a representation of typical frequency response of a SAW filter
• FIGURE 2 is a representation of a Dirac Delta Function
• FIGURE 3 is a representation of an impulse response of a SAW filter
• FIGURE 4 is a representation of a Pulse Train
• FIGURE 5 is an output response of a SAW filter
• FIGURE 6 is a table showing number of pulses vs. peak power
• FIGURE 7 is a representation of a Pulse Train
• FIGURE 8 is an output response of a SAW filter
• FIGURE 9 is a table showing number of pulses vs. peak power
• FIGURE 10 is a table showing number of pulses vs. peak power
• FIGURE 1 J is a representation of a Pulse Train Generator
• FIGURE 12 is a block diagram of a modulator.
• the invention disclosed in this application uses any integer cycle, ultra-wide band, or impulse type modulation and more particularly is designed to work with a method of modulation named xMax which has been described above.
• the impulse response of a filter is usually derived by passing a Dirac delta signal (simply known as delta function) at the input of the SAW filter.
• the Delta function is defined as:
• the Dirac Delta fiinction often referred to as the unit impulse or delta function, is the function that defines the idea of a unit impulse. This function is one that is infinitesimally narrow, infinitely tall, yet integrates to unity, one. This function can be visualized as shown in figure 2:
• Figure 9, Table 2 shows the relationship between the number of pulses, duration of the pulses, and peak amplitude of the SAW filter output:
• the amplitude of the input pulses is lVpp.
• the SAW filter output amplitude also depends on the peak amplitude of the pulses applied at the input of the SAW filter.
• the output amplitude increases with the increase of the input signal amplitude. For example consider a pulse train of seven pulses; the period of the pulses is 1.109ns with a 50% duty cycle. If the input amplitude is increased from lVpp to 5Vpp, the corresponding output amplitude of the SAW filter increases.
• Figure 10, Table 3 is derived by changing the input amplitude of the pulses while keeping the period and duty cycle of the pulses constant.
• the circuit of figure 11 is used to generate a pulse train of five pulses each with a period of lnsec using a single Snsec pulse.
• a single pulse of 5nsec is applied to a two input AND/NAND Gate.
• the inverted output of the gate is fed to its inverted input through a programmable delay chip.
• the programmable delay can also be implemented using a coaxial cable.
• the programmable delay is adjusted such that the propagation delay of the AND/NAND gate together with programmable delay equals lnsec.
• a feedback loop is formed from the output of the gate to its input. This circuit produces a pulse train of five pulses with a period of lnsec.
• a block diagram of a modulator implementing the disclosure of this invention is shown in figure 12 and operates as follows.
• the data source provides encoded index-N data.
• the data could be single ended or differential.
• the data format could either be NRZ (Non Return to Zero) or RZ (Return to zero).
• the peak-to-peak amplitude of this signal can either be programmable or fixed. Since it is a digital signal, it can be TTL, CMOS, ECL, PECL, LVDS or any other logic family.
• Encoded data from the data source is fed into the Pulse Train Generator circuit. This block can be implemented in a number of ways, two of which were discussed above. There are also shown in figure 12 two matching networks.
• the input-matching network transforms the impedance of the pulse train generator into the input impedance of the SAW filter. It is also used to convert differential data output into single ended output. Similarly the output-matching network performs impedance transformation from the SAW filter to the next stage.
• Matching networks can be implemented using either discrete components or active networks. Any SAW filter with an appropriate bandwidth and appropriate impulse response can be used as modulator.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Power Engineering (AREA)
• Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
• Transmitters (AREA)
• Amplitude Modulation (AREA)

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• 2007
  • 2007-08-31 US US11/897,648 patent/US7782975B2/en not_active Expired - Fee Related
  • 2007-09-01 MX MX2009001709A patent/MX2009001709A/es active IP Right Grant
  • 2007-09-01 WO PCT/US2007/019236 patent/WO2008030406A2/en active Application Filing
  • 2007-09-01 AU AU2007293410A patent/AU2007293410A1/en not_active Abandoned
  • 2007-09-01 CA CA002661619A patent/CA2661619A1/en not_active Abandoned
  • 2007-09-01 EP EP07837657A patent/EP2064821A4/en not_active Withdrawn

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